[julia-users] Merging dataframes

[Joosep Pata]

Is there a way to avoid copying when doing vcat(df1::DataFrame, df2::DataFrame, 
…)? I’m trying to open hundreds of files with DataFrames, merge all of them and 
save a single ~150M row x 100 col DataFrame using HDF5 and JLD (to be opened 
later using mmap), and it seems to work marvelously, apart from the vcat.
Does a no-copy option exist? I’m aware of DataStreams as a concept, but as I 
understand, they’re not fully fleshed out yet.